The present invention generally relates to dialysis systems. More specifically, the present invention relates to regeneration dialysis systems and continuous flow dialysis systems. The present invention also relates to methods of performing dialysis therapies.
Due to disease, insult or other causes, a person's renal system can fail. In renal failure of any cause, there are several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load is no longer possible in renal failure. During renal failure, toxic end products of nitrogen metabolism (urea, creatinine, uric acid, and others) can accumulate in blood and tissues.
Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins and excess water from the body that would otherwise have been removed by normal functioning kidneys. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life saving. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys.
Hemodialysis and peritoneal dialysis are two types of dialysis therapies commonly used to treat loss of kidney function. Hemodialysis treatment utilizes the patient's blood to remove waste, toxins and excess water from the patient. The patient is connected to a hemodialysis machine and the patient's blood is pumped through the machine. Catheters are inserted into the patient's veins and arteries to connect the blood flow to and from the hemodialysis machine. As blood passes through a dialyzer in the hemodialysis machine, the dialyzer removes the waste, toxins and excess water from the patient's blood and returns the blood to infuse back into the patient. A large amount of dialysate, for example about 120 liters, is used to dialyze the blood during a single hemodialysis therapy. The spent dialysate is then discarded. Hemodialysis treatment lasts several hours and is generally performed in a treatment center about three or four times per week.
One type of hemodialysis therapy is regenerative hemodialysis. This therapy uses a hemodialysis system, which includes a cartridge for dialysate regeneration. One such cartridge is manufactured under the name REDY™ by Sorb Technology, Oklahoma City, Okla. In this system, the dialysate fluid flow path must be properly cleaned before the hemodialysis machine can be used on another patient. Also, the dialysate fluid flow path is not a closed system, i.e., the dialysate fluid flow path is open to the atmosphere, such that oxygen from the atmosphere can contact fluid in the system and foster the growth of bacteria in same. Consequently, contamination of such a dialysis system can be a concern. Further, the dialysate fluid exiting the REDY™ cartridge is not suitable for peritoneal dialysis because the fluid is relatively acidic and not, therefore, physiologic. Moreover, this system requires the attention of medical personnel during therapy.
Peritoneal dialysis utilizes a sterile, pyrogen free dialysis solution or “dialysate”, which is infused into a patient's peritoneal cavity. The dialysate contacts the patient's peritoneal membrane in the peritoneal cavity. Waste, toxins and excess water pass from the patient's bloodstream through the peritoneal membrane and into the dialysate. The transfer of waste, toxins, and water from the bloodstream into the dialysate occurs due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. The spent dialysate drains from the patient's peritoneal cavity and removes the waste, toxins and excess water from the patient. This cycle is repeated on a semi-continuous or continuous basis.
There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis (“CAPD”) and automated peritoneal dialysis. CAPD is a manual dialysis treatment, in which the patient connects an implanted catheter to a drain and allows a spent dialysate fluid to drain from the peritoneal cavity. The patient then connects the catheter to a bag of fresh dialysate and manually infuses fresh dialysate through the catheter and into the patient's peritoneal cavity. The patient disconnects the catheter from the fresh dialysate bag and allows the dialysate to dwell within the cavity to transfer waste, toxins and excess water from the patient's bloodstream to the dialysate solution. After a dwell period, the patient repeats the manual dialysis procedure.
In CAPD the patient performs several drain, fill, and dwell cycles during the day, for example, about four times per day. Each exchange or treatment cycle, which includes a drain, fill and dwell, takes about four hours. Manual peritoneal dialysis performed by the patient requires a significant amount of time and effort from the patient. This inconvenient procedure leaves ample room for improvement and therapy enhancements to improve patient quality of life.
Automated peritoneal dialysis is similar to continuous peritoneal dialysis in that the dialysis treatment includes a drain, fill, and dwell cycle. However, a dialysis machine automatically performs three to four cycles of peritoneal dialysis treatment, typically overnight while the patient sleeps.
With automated peritoneal dialysis, an automated dialysis machine fluidly connects to an implanted catheter. The automated dialysis machine also fluidly connects to a source or bag of fresh dialysate and to a fluid drain. The dialysis machine pumps spent dialysate from the peritoneal cavity, though the catheter, to the drain. The dialysis machine then pumps fresh dialysate from the dialysate source, through the catheter, and into the patient's peritoneal cavity. The automated machine allows the dialysate to dwell within the cavity so that the transfer of waste, toxins and excess water from the patient's bloodstream to the dialysate solution can take place. A computer controls the automated dialysis machine so that the dialysis treatment occurs automatically when the patient is connected to the dialysis machine, for example, when the patient sleeps. That is, the dialysis system automatically and sequentially pumps fluid into the peritoneal cavity, allows for dwell, pumps fluid out of the peritoneal cavity, and repeats the procedure.
Several drain, fill, and dwell cycles will occur during the treatment. Also, a “last fill” is often used at the end of the automated dialysis treatment, which remains in the peritoneal cavity of the patient when the patient disconnects from the dialysis machine for the day. Automated peritoneal dialysis frees the patient from having to manually performing the drain, dwell, and fill steps. Automated dialysis can improve the patient's dialysis treatment and undoubtedly improves the patient's quality of life.
So-called “continuous flow” peritoneal dialysis (“CFPD”) systems that purport to provide continuous dialysate flow exist. However, these systems typically have a single pass fluid flow. That is, the dialysate flows into, through, and out of the peritoneal cavity one time before being sent to a drain. The “spent” dialysate (waste laden dialysate) from the patient collects in a drain bag, which is discarded, or runs into a household drain or other drain. Known CFPD systems, therefore, typically use a volume of dialysate one time and then discard it. That is, the systems have no ability to regenerate or reuse a quantity of dialysate.
The effectiveness of existing peritoneal dialysis therapies, and existing systems which perform the therapies, depends upon the amount of dialysis fluid used. For example, typical peritoneal dialysis therapy requires about 4 to 6 exchanges of dialysate (drain, fill, dwell) with about 2 to 3 liters of dialysate for each exchange. Peritoneal dialysis is a daily therapy performed 7 days per week. As a consequence, 240 to 540 liters of fresh dialysate must be delivered to and stored at a patient's home each month. Increasing dialysate dosage to increase therapy effectiveness will necessitate even more dialysate.
Therefore, needs exist to provide improved dialysis systems and methods of performing dialysis. Particularly, needs exist to provide closed loop peritoneal dialysis systems and methods that regenerate or reuse spent dialysate. There are needs for such systems and methods to be compatible with CFPD treatment so that patients can perform the procedure at home without the need for storing an inordinate amount of fresh dialysate bags. There are further needs for such systems and methods to be automated so that the procedure can be largely performed at night while the patient sleeps.